David Ortiz wasn't chugging cheap champagne during his crazy World Series celebration last night -- the stuff Big Papi was pounding runs $100,000 per bottle ... TMZ has learned.
You've seen the pics -- Ortiz hoisting a giant gold bottle of bubbly, while the rest of his Boston Red Sox teammates celebrated their victory over the St. Louis Cardinals.
Now, we've learned ... the booze was a 15 litre bottle of Armand de Brignac Nebuchadnezzar Champagne, also known as "Ace of Spades" ... and it runs between $100k and $150k in the club scene.
These bottles are SUPER rare -- a Russian billionaire once splurged on a bottle for Zac Efron and Heather Graham when he spotted the actors at a bar in Chicago.
So, when Ortiz got up this morning and went to the bathroom -- ya might say he was pissing money away.